More grandparents prefer hard copy over digital copy
Answer:
One's place
Step-by-step explanation:
Answer:
Nirmala can use the lamp for 31.66 hours before it runs out of oil.
Step-by-step explanation:
From the graph,
Take any two points, let say
(15, 25)
(25, 10)
![\mathrm{Slope\:between\:two\:points}:\quad \mathrm{Slope}=\frac{y_2-y_1}{x_2-x_1}](https://tex.z-dn.net/?f=%5Cmathrm%7BSlope%5C%3Abetween%5C%3Atwo%5C%3Apoints%7D%3A%5Cquad%20%5Cmathrm%7BSlope%7D%3D%5Cfrac%7By_2-y_1%7D%7Bx_2-x_1%7D)
![\left(x_1,\:y_1\right)=\left(15,\:25\right),\:\left(x_2,\:y_2\right)=\left(25,\:10\right)](https://tex.z-dn.net/?f=%5Cleft%28x_1%2C%5C%3Ay_1%5Cright%29%3D%5Cleft%2815%2C%5C%3A25%5Cright%29%2C%5C%3A%5Cleft%28x_2%2C%5C%3Ay_2%5Cright%29%3D%5Cleft%2825%2C%5C%3A10%5Cright%29)
![m=\frac{10-25}{25-15}](https://tex.z-dn.net/?f=m%3D%5Cfrac%7B10-25%7D%7B25-15%7D)
![m=-\frac{3}{2}](https://tex.z-dn.net/?f=m%3D-%5Cfrac%7B3%7D%7B2%7D)
The equation of line in slope-intercept form
![y = mx + b](https://tex.z-dn.net/?f=y%20%3D%20mx%20%2B%20b)
Putting
and any point, let say (25, 10), to find the y-intercept 'b'
![10=-\frac{3}{2}\left(25\right)+b](https://tex.z-dn.net/?f=10%3D-%5Cfrac%7B3%7D%7B2%7D%5Cleft%2825%5Cright%29%2Bb)
![-\frac{3}{2}\left(25\right)+b=10](https://tex.z-dn.net/?f=-%5Cfrac%7B3%7D%7B2%7D%5Cleft%2825%5Cright%29%2Bb%3D10)
![-\frac{75}{2}+b=10](https://tex.z-dn.net/?f=-%5Cfrac%7B75%7D%7B2%7D%2Bb%3D10)
![\mathrm{Add\:}\frac{75}{2}\mathrm{\:to\:both\:sides}](https://tex.z-dn.net/?f=%5Cmathrm%7BAdd%5C%3A%7D%5Cfrac%7B75%7D%7B2%7D%5Cmathrm%7B%5C%3Ato%5C%3Aboth%5C%3Asides%7D)
![-\frac{75}{2}+b+\frac{75}{2}=10+\frac{75}{2}](https://tex.z-dn.net/?f=-%5Cfrac%7B75%7D%7B2%7D%2Bb%2B%5Cfrac%7B75%7D%7B2%7D%3D10%2B%5Cfrac%7B75%7D%7B2%7D)
![b=\frac{95}{2}](https://tex.z-dn.net/?f=b%3D%5Cfrac%7B95%7D%7B2%7D)
![b=47.5](https://tex.z-dn.net/?f=b%3D47.5)
So the equation of line will be:
![y = mx + b](https://tex.z-dn.net/?f=y%20%3D%20mx%20%2B%20b)
![y=-\frac{3}{2}x+47.5](https://tex.z-dn.net/?f=y%3D-%5Cfrac%7B3%7D%7B2%7Dx%2B47.5)
In order to find how long Nirmala can use the lamp before it runs out of oil, we need to find x-intercept which can be obtained by putting y = 0, and solve for x, as duration lies on x-axis.
so
![y=-\frac{3}{2}x+47.5](https://tex.z-dn.net/?f=y%3D-%5Cfrac%7B3%7D%7B2%7Dx%2B47.5)
Putting y = 0
![0=-\frac{3}{2}x+47.5](https://tex.z-dn.net/?f=0%3D-%5Cfrac%7B3%7D%7B2%7Dx%2B47.5)
![-\frac{3}{2}x+47.5=0](https://tex.z-dn.net/?f=-%5Cfrac%7B3%7D%7B2%7Dx%2B47.5%3D0)
![-\frac{3}{2}x=-47.5](https://tex.z-dn.net/?f=-%5Cfrac%7B3%7D%7B2%7Dx%3D-47.5)
![\mathrm{Multiply\:both\:sides\:by\:}2](https://tex.z-dn.net/?f=%5Cmathrm%7BMultiply%5C%3Aboth%5C%3Asides%5C%3Aby%5C%3A%7D2)
![2\left(-\frac{3}{2}x\right)=2\left(-47.5\right)](https://tex.z-dn.net/?f=2%5Cleft%28-%5Cfrac%7B3%7D%7B2%7Dx%5Cright%29%3D2%5Cleft%28-47.5%5Cright%29)
![-3x=-95](https://tex.z-dn.net/?f=-3x%3D-95)
![\mathrm{Divide\:both\:sides\:by\:}-3](https://tex.z-dn.net/?f=%5Cmathrm%7BDivide%5C%3Aboth%5C%3Asides%5C%3Aby%5C%3A%7D-3)
![\frac{-3x}{-3}=\frac{-95}{-3}](https://tex.z-dn.net/?f=%5Cfrac%7B-3x%7D%7B-3%7D%3D%5Cfrac%7B-95%7D%7B-3%7D)
![x=\frac{95}{3}](https://tex.z-dn.net/?f=x%3D%5Cfrac%7B95%7D%7B3%7D)
![x=31.66](https://tex.z-dn.net/?f=x%3D31.66)
Therefore, Nirmala can use the lamp for 31.66 hours before it runs out of oil.